Brake Systems & Safety Flashcards

What is 'buff and draft' loading in relation to train brake handling, and why does it matter?

Answer: Compressive (buff) and tensile (draft) forces along the train that can cause derailments if mismanaged

Buff (compressive) and draft (tensile) forces act along the coupler line; abrupt brake applications can create dangerous in-train forces leading to derailment or equipment damage.

When must a locomotive engineer conduct a 'set and release' brake test after switching operations?

Answer: Before departing if cars have been added, removed, or brake hoses reconnected

FRA rules require a brake test whenever the train consist is modified or brake connections are disturbed to ensure all connected brakes are operative.

What is the purpose of the 'actuating pipe' (or signal pipe) in some automatic brake systems?

Answer: It provides a separate faster-propagating signal to trigger emergency brake applications ahead of the pressure wave

The actuating pipe carries an emergency signal that propagates faster than the brake pipe pressure drop, allowing near-simultaneous brake application along the entire train length.

A helper locomotive is cut in at the rear of a heavy train on a mountain grade. What brake handling concern is most critical?

Answer: Coordinated brake applications are essential to avoid buff forces that could cause a derailment

Uncoordinated braking between head-end and helper locomotives can create extreme compressive buff forces mid-train, potentially causing a derailment.

What is the recommended procedure when a locomotive engineer suspects a 'hanging brake' (brake not fully releasing) on a car in the train?

Answer: Stop the train, inspect the suspected car, and tag it out of service if the brake cannot be released

A hanging brake generates excessive heat and can cause wheel damage or fire; the train must be stopped and the car inspected and tagged out if the defect cannot be corrected.

Under Positive Train Control (PTC), what happens to the locomotive brakes if the engineer fails to acknowledge an overspeed alarm within the required time?

Answer: The PTC system enforces a penalty brake application, placing brakes in emergency

PTC enforces speed compliance by triggering a penalty brake application if the engineer does not acknowledge and respond to an overspeed condition within the required acknowledgment window.

What is 'dynamic brake blending,' and what is its advantage over using dynamic brakes alone?

Answer: Automatically coordinating dynamic and air brakes so total braking force remains constant as dynamic brake capacity varies with speed

Dynamic brake blending systems automatically add air brakes as dynamic brake effectiveness decreases at low speeds, providing consistent deceleration throughout the speed range.